The present invention relates to a separator of solid particles, particularly of soot from exhaust gas of an internal combustion engine by means of an electrical filter which includes a source of direct current high voltage, a tubular housing connected to the positive pole of the voltage source and an axially arranged central electrode carrying a plurality of electrical discharge points directed toward the inner wall of the filter housing and being spaced from the latter.
In known devices of this kind called also soot deflectors (German publication DE-OS No. 31 41 156) the electric discharging points are arranged on the upper surface of the so-called spray discharge discs, the latter being arranged parallel to each other on a support extending parallel to the filter housing. When high voltage is applied to the discharge point, a corona discharge will occur causing ionization of molecules of the exhaust gas. Electrons freed during the corona discharge land on solid particles, or soot particles in the gas and impart to the particles a negative charge. Consequently, the negatively charged solid particles are attracted to and deposited on the positively charged inner wall of the filter housing. In order to prevent the precipitation of oppositely charged particles on the spray discharge discs and hence the impairment of the corona discharge, the spray discharge discs are constructed of an extremely thin material having for example the thickness of only 0.05 mm, and are clamped to the support only at their center points. In this manner, the tips of the spray discharge discs are brought into vibrations in response to vibrations of the motor vehicle and the deposited particles are shaken off. In practice, however, it has been found that due to high flow speeds in the filter and also due to high shocks from the motor vehicle, the spray discharge discs are subject to a directional vibration flatter and damage each other. To avoid this detrimental effect, the spray discharge discs have been additionally reinforced in the range of the support. Consequently, a relatively heavy central electrode has resulted. A central electrode having increased weight, however, requires for its mount in the filter housing very stable high voltage insulators which must be also increased in size and weight. Large insulators also require substantially more energy for burning the deposited solid particles in comparison with smaller insulators.